Carburetor



CARBURETOR Filed Aug. 9, 1929 2 Sheets-Sheet l E N K m B M E G R O E G INVENTOR ATTORNEY Aug. 16, 1932. I G M, B|CIKNELL 1,872,559

3 CARBURETOR Filed Aug. 9, 1 929 2 Sheets-Sheet 2 GEORGE M BICKNELL INVENTOR ATTORNEY by the suction of the air stream.

Patented Aug. 16, 1932 UNITED STATES PATENT orifice GEORGE M. BICKNELL, OF ST. LOUIS, MISSOURI, A S SIGNOIt TO CARTER GARBURETOB CORPORATION, OF ST. LOUIS, MISSOURI, A COBPORATION OF DELAWARE OABIB'URETOB Application ma August a, 1929. Serial No. 384,610,

This invention relates to carburetors for internal combustion engines.

It is an object of the invention to produce a carburetor in which the fuel will only have to be lifted a very short distance fromf the fuel level in the supply chamber or float bowl It is a further object of this invention to produce a carburetor in which the air and fuel passageways are short and direct'without sacrificing any efficiency in mixing qualities.

A further object of this invention is to produce a carburetor in which the velocity of the flow of air is built up smoothly until it reaches the point where the highest velocity is required, and then permitted to slow down gradually as it passes from the carburetor.

Other objects of the invention will appear from the following description and the accompanying drawings, referring to which:

Figure 1 is a plan view of a carburetor constructed according to my invention.

Figure 2 is a sectional elevation of the carburetor shown in Figure 1, sections being taken along the line 2 -2 looking in the direction of the arrows.

Figure 3 is an end elevation of the carburetor shown in Figures 1 and 2.

Figure 4 is an end elevation with parts in section of the carburetor shown .in Figures 1, 2, and 3 taken from the end opposite to that shownjin Figure 3.

Figure 5 is a detail view of the pump outlet nozzle structure.

j The reference numeral 1 indicates a casting forming the main body member of the carburetor. This casting is provided at one end with a flange 2 having bolt holes 3 by means of which the carburetor maybe secured to the intake manifold of an internal combustion engine. At the end opposite the flange 2 is a somewhat enlarged portion 4. The passageway 5 of substantially circular cross section throughout is formed in the casting. The passage is restricted, as indicated at 6, and gradually enlarged again, as indicated at 7, to form a venturi at the throat of which the speed of flow of the air is considerably increased. The discharge end of the passageway terminates in a cylindrical portion 8,'as shown.

The flow of air through the carburetor is controlled by two valves comprising a choke valve 9 and a throttle valve 10, the choke valve being, in this instance, mounted on a o vertical shaft 11, and the throttle valve being mounted on the shaft 12. Suitable screws 13 i are provided to attach the throttle valve to the shaft 12. The choke valve shaft is split to receive the valve 11, which is attached to it by solder'or any other suitable means (not shown). a A suitable operating lever 14 is attached to the choke shaft 11 and a spring 15 is provided to yieldably hold the choke in closed position. A throttle operating lever 16 is suitably attached to the shaft 12 of the throttle.

k The fuel is supplied to the inlet 64' of the carburetor from any conventional source, as by gravity feed from the .main supply tank or from a vacuum tank, or it may be supplied from a fuel pump. It is maintained at a constant-level in the fuel bowl 17 by the float 23. The main nozzle member 24c is threaded ed on the wire 26 to close the port 51, as indirovided.

cated. The metering wire 26 is with a ortion 27 of smaller or di erent diameter from the main part of the wire. This substantially at the level of the outlet of the nozzle 24. This'venturi discharges into the main venturi just inside of its throat and inside the choke valve 9. One or more air inlet ports 32 are formed in the entrance of the main venturi and connected to an annular space 33 surrounding the choke tube 31. The entrance to these air inlets 32 is outside the choke valve, and air may by-pass the choke valve by flowing through the passages 32, 33, and 31.

A small bore 34 is formed in the member 19 to permit fuel to flow from the bore 23 to a chamber 35 which is threaded to receive an idling tube 36. This tube communicates with passages 37 and 38 in the main body member of the carburetor which lead to a port 39 at the edge of the throttle valve 10. An air bleed 40 is formed to admit air from the main mixing chamber 41 to the idling duct.

, A11 accelerating pump cylinder 42 is threaded to the main bod member at 43, and a passageway 44 leads rom the lower end of the cylinder through the threaded portion, as shown, to communicate with the bore 45 in the body member. A small tube 46 is threaded into the body member to communicate with the bore 45, and an inwardly opening check valve 47 is mounted in the tube. It will be understood that the lower end of the tube is below the fuel level in the float 'cylin er of the pump. A longitudinal bore bowl. A jet nozzle 48 is threaded into the body member in communication with the bore 45 and arranged to discharge through a minute orifice 49 just outside the choke valve 9, and an outwardly opened ball check valve 50 is mounted in the jet nozzle 48.

The accelerating pump nozzle comprises a body member 48 having screw threads 71 for attachment to the corresponding threads in the body of the carburetor, and a jet member or nozzle proper 72, which vis threadedor otherwise attached to the body member 48 as shown. The nozzle body 48 is bored transversely at 64 to provide communication throu h the bores 55, 45, and 44 with the 56 in the nozzle body is provided with a shoulder or valve seat 57 to receive the ball check 50. The ball check is retained by the member 72, which has an axial bore 58 terminating in a minute orifice or jet 49.

An important feature of the nozzle is the sealing means, as the leakage of air into the accelerating pump system, or fuel out of it, might upset the calibration of the carburetor. In order to produce an effective sealing means, I form a shoulder or head 60 having a fairly abrupt taper, and aseating part 61,

having a slow taper and a thin wall. The spacing of thesetapered parts is such that the slim taper 61 seats first, and the thin walls 61 are slightly distorted as the nozzle body is brought up against the seat 60. A very positive seal is formed in that manner.

The operation of the device is as follows:

Fuel being supplied to the fuel bowl by suitable means and maintained therein substantially at .the level indicated at AA, the fuel flows through the passages 22 and 25 to the main nozzle 24. It also flows through port 53 in the wall of the main nozzle and the passage 34 to the idling duct 36.

It being desired to start the engine, the choke valve 9 is closedand the throttle valve 10 suitably adjusted, if desired. This may be done either manually or by connection to the choke valve operating means. Such means, however, forms no part of this invention and is not shown.

When the engine is operated by the starting means, air is-drawn through the passages 32 to the choke tube 31 in which it is brought to a comparatively high velocity in the restricted portion of the venturi therein. Inasmuch as the fuel is at a level comparatively near the top of the nozzle, fuel is readily lifted through the nozzle by the suction in the venturi,'together with air, which may be drawn in through the ports 53. It will be understood that the nozzle does not fit'closely in the bore 54 and that air may ass downwardly through the crevice therebetwe'en to enter the nozzle through the ort 53 and form an emulsion therein. T is emulsion is comparatively li ht in specific gravity and is readily lifte through the short distance between the fuel level and the top of the nozzle.

At the top of the nozzle, the emulsion is broken upinto a spray mixture with the rapidly flowing air passing through the venturi, thus forming a very rich mixture which is suitable for starting purposes, which mixture flows into the engine charging it in the usual manner.

After the engine has been started and warmed up to some extent, the choke valve 9 is opened to permit the rich mixture issuing from the-venturi 31 to be diluted and further mixed with fresh air in the main mixing chamber 41.

When the throttle is closed, a comparatively high suction will exist in the suction chamber 55 at the outlet side of the throttle valve 10, while substantially atmospheric pressure may exist in the mixing chamber 41. Under these conditions, suction will be produced in the passage 38, drawing air in through the bleed 40 and drawin fuel up through the idling tube 36, thus orming a mixture suitable for idling conditions.

The piston 76 of the pump is operated downwardly when the throttle is opened and when it is closed, with the result upwardly ened, a quantity that when the throttle is o v of fuel will be discharge through the jet Y a metering wire extending through said metering orifice and through said mixing conduit for controlling the flow of fuel to said conduit, an opening of comparatively large size in a wall of said conduit to receive said wire, and a cover slidably mounted on said wire and adapted to closesaid opening, said cover being adapted tobe held firmly in closed position by suction in mixing conduit- 2. In a carburetor, means forming a mix- 1 ing conduit, a control valve for'said conduit, a metering wire passing through said conduit at a point adjacent said control valve, said valve; being mounted to rotate on an axis parallel to said wire and adjacent thereto, whereby the combined resistance of said Wire and said valve will be reduced to a minimum when the valve is open.

3. In a carburetor, a horizontal passage- Way of substantially circular cross section,"a

venturi in said passageway through which,

the air must pass at a high velocity, a float chamber mounted directly under said passageway, a vertically disposed primary choke tube extending into saidfloat chamber from said passageway, said choke tube being adapted to d scharge a mixture of air and fuel into said passageway at a point inside said venturi, an annular well surrounding said choke tube, and an air passage leading from a point in said main air passage'outside the venturi to said well.

4.. In a carburetor, means forming a mixing conduit, a venturi in said coduit, a manu-j ally operable valve mounted near the throatof said venturi to control the flow therethrough, and manually operated means comprising a pump for discharging a jet of fuel agalnst said valve.

5. In a plain tube carburetor, mg a mixin conduit, throttle and choke valves contro 'ng the flow of fuel through said conduit, an accelerating pump connected to said throttle to discharge fuel upon an opening movement thereof, and a discharge nozzle for said, pump, said nozzle being mounted to discharge into said mixingconof many modifications, and, ac-

ing the conducting paratively thin wall with a slim taper,

means form- 6. In a carburetor, a member havinga fuel passageway therein, a bore in said member intersecting said passageway, a fluid conducting member having an axial passageway said passageway, and means for sealing said conducting member within saidbody membercomprising a pair of seats, one of said seats having a slim, taper, and the other of said seats having an abrupt taper.

8. Ina device of the class described, a body member having a passa eway therein, a bore passageway, a conducting member adapted to be inserted within said bore and to be sealed to prevent leakage from said passageway through said bore, and means for sealmember in said bore comprising two seats adapted to fit the bore, one on each side of said passageway, one of said seats having a comparatively thin wall with a slim taper, the other of said seats being constructed-to seat abruptly and positively.

9. In a device of the class described, a body member having a passageway therein, a bore through said body member intersecting said passageway, a conductin member adapted to be inserted within sa1d bore and to be sealed to prevent leakage from said passageway through said bore,1and means for sealing the conducting member in said bore comprising two seats on said member adapted to fit the bore, one'on each side of said passaid seats having a comthe other of! said seats being constructed to seat abruptly and positively, and screw threaded means between said seats for attaching said conducting member to 'said body member.

In testimony whereof, I aflix my signature this 30th day of July, 1929. GEORGE M. BICKNELL.

sageway, one of duit at a oint between the inlet end and said choke va ve.

90 through said body mem er intersecting said 

